Systems and methods for selecting a gateway general packet radio service (GPRS) support node

ABSTRACT

in one aspect, the present invention provides a method for selecting a GGSN. The method may include obtaining a network address for a home agent; transmitting a request to a name server for a name associated with the network address; receiving from the name server in response to the request a name associated with the network address; initiating a GPRS attachment; and after initiating the GPRS attachment, initiating a PDP context activation, wherein the step of initiating the PDP context activation comprises transmitting the name to an SGSN, and the SGSN is configured to use the name to lookup an IP address of a GGSN.

This application is a continuation of U.S. patent application Ser. No.12/991,476, filed Nov. 8, 2010, which is a 371 of PCT/EP2008/055739filed May 9, 2008, the disclosures of which are incorporated herein byreference.

TECHNICAL FIELD

The present invention relates generally to the field of mobile IP.

BACKGROUND

Many mobile stations (or “user equipment” (UE)) are now configured so asto be able to obtain access to the Internet, (or other IP network)through a variety of access networks. For example, a mobile station mayobtain access to the Internet through a non-3GPP defined access network(e.g., a WLAN/WiFi network) and through a radio access network (RAN),such as a 3GPP RAN (e.g., a GSM/EDGE RAN (GERAN), UTRAN, etc.). In therest of this document we will use Wireless LAN (WLAN) to exemplify anon-3GPP access technology. It should however be understood that othernon-3GPP access technologies may be used as well.

When a mobile station accesses the internet using a WLAN accessnet-work, the mobile station may make use of a Home Agent (HA), and whena mobile station accesses the internet using a 3GPP access network, themobile station may make use of a GRPS backbone network, which includes aServing GPRS Support Node (SGSN) and a Gateway GPRS Support Node (GGSN).3GPP is defining a solution for IP session continuity when a mobilestation moves from accessing the Internet through a WLAN to accessingthe Internet though a 3GPP RAN. To facilitate this IP sessioncontinuity, it has been proposed to collocate the HA function with theGGSN (e.g., provide a GGSN with software for implementing an HA).

One of the main benefits with combining HA and GGSN into a single nodeis that it is possible to avoid Mobile IP specific signaling and userplane overhead when a mobile station is accessing the Internet via GPRS.This is accomplished by treating the GPRS access as a “home link” forthe mobile station. A “Home link” is a specific case for Dual StackMobile IPv6 (DSMIPv6) when the mobile station uses an access where theIP address allocated to the mobile station in that access is equal tothe Home Address (HoA) allocated to the mobile station by the DSMIPv6HA. Corresponding “home link” functionality is present also in otherMobile IP variants such as Mobile IPv6 (MIPv6) and Mobile IPv4 (MIPv4).DSMIPv6 is used in the descriptions of the embodiments but it should beunderstood that also other variants of Mobile IP may be used.

When a mobile station is using GPRS access, DSMIPv6 is not activated andIP access is provided to the mobile station using regular GPRSprocedures only. When the mobile station is using WLAN access (e.g.,I-WLAN access), the mobile station receives a Care-of Address (CoA) fromthe Packet Data Gateway PPDG) and connects to the HA function in GGSN/HAusing DSMIPv6. The IP address assigned in GPRS (PDP address) is the sameas the IP address assigned via DSMIPv6 (Home Address).

With the combined GGSN/HA it is required that the same GGSN/HA entity isselected when the mobile station is using GPRS and I-WLAN. One issuewith this is that GGSN selection mechanisms are different from HAselection mechanisms.

GGSN selection in GPRS is done by the SGSN based on an Access Point Name(APN). APN information may be received from the HLR, from the mobilestation or be pre-configured in the SGSN. Based on the informationreceived from the mobile station, the HLR or that is preconfigured inthe SGSN, the SGSN creates an APN string that is resolved in DNS. In thereply from DNS, the SGSN receives one or more IP addresses to GGSN(s)that support the requested APN.

HA selection for DSMIP6 may be done in different ways. One optionspecified for I-WLAN mobility is that the mobile station resolves a “HAAPN” in DNS. Note that this DNS system is accessible to the mobilestation and logically separate from the GPRS core network internal DNSsystem used by SGSN. In the reply from DNS, the mobile station receivesone or more IP addresses to HA(s) that support the requested HA APN.

What is desired are systems and methods for selecting a support node sothat the same GGSN/HA entity is selected when a mobile stationtransitions WLAN access to GPRS access.

SUMMARY

In one aspect, the present invention provides a method for selecting asupport node (e.g., a GGSN or other support node). In some embodiments,the method includes: obtaining a network address for an agent (e.g., aHome Agent in a mobile IP system); transmitting a request to a nameserver (e.g., a domain name server or other name server) for a nameassociated with the network address; receiving from the name server inresponse to the request a name associated with the network address;initiating a network attachment (e.g., a GPRS attachment); and afterinitiating the network attachment, initiating a context activation(e.g., a PDP context activation), wherein the step of initiating thecontext activation comprises transmitting the name to a second supportnode (e.g., a SGSN). The second support node may be configured to selectanother support node (e.g., a GGSN) based on the received name. In someembodiments, the step of selecting the other support node based on thereceived name comprises transmitting a request to a second name serverfor a network address associated with the name. The second name servermay be different than the first recited name server (e.g., the secondname server may be a GPRS internal name server). The step oftransmitting the request to the name server may be performed prior tothe step of initiating the network attachment and The network addressmay be an Internet Protocol (IP) address.

In another aspect, the invention provides an improved mobile station. Insome embodiments, the improved mobile station that is operable to:obtain a network address for an agent; access a network using the agent;transmit a request to a name server for a name associated with thenetwork address; receive from the name server a name associated with thenetwork address; initiate a network attachment; and after initiating thenetwork attachment, transmit to a support node the name received fromthe name server. Preferably, the support node is configured to selectanother support node based on the received name.

In another aspect, the present invention provides an improvedcommunication system. In some embodiments, the improved communicationsystem includes: a GPRS network comprising an SGSN, a combined GGSN/HAnode, and a first name server; and a second name server, wherein thesecond name server is configured to map a network address associatedwith the HA function of the combined GGSN/HA node to a name, and thefirst name server is configured to map the name to a network addressassociated with the GGSN function of combined GGSN/HA node.

The above and other aspects and embodiments of the present invention aredescribed below with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and form partof the specification, illustrate various embodiments of the presentinvention. In the drawings, like reference numbers indicate identical orfunctionally similar elements.

FIG. 1. illustrates a communication system according to embodiments ofthe invention.

FIG. 2 is a flow chart illustrating a process according to someembodiments for selecting a GGSN.

FIG. 3 is a functional block diagram of a mobile station (MS) accordingto embodiments of the invention.

DETAILED DESCRIPTION

In one aspect, the present invention provides systems and methods forselecting a GGSN.

Referring now to FIG. 1, FIG. 1 illustrates a communication system 100according to an embodiment of the invention. More specifically, FIG. 1illustrates a mobile station. 102 that can access a packet data network104 (e.g., the Internet or other IP network; through a WLAN AN 106 andthrough a 3GPP RAN 108 and GPRS network 110. GPRS network 110 includesan SGSN 112, a GGSN/HA 114 (e.g., conventional GGSN with HAfunctionality added), and a domain name server (DNS) 116, A seconddomain name server 118 is accessible via network 104.

Referring now to FIG. 2, FIG. 2 is a flow chart illustrating a process200 for selecting a GGSN in the environment shown in FIG. 1. Process 200may begin in step 202, where the mobile station (MS) 102 obtains an IPaddress associated with the HA function of the GGSN/HA 114 and accessesthe network 104 through the WLAN Access Network 106, for example, MS 102may establish an IP session with a server 120 connected to network 104.

In step 204, MS 102 transmits to DNS 118 a request for a reverse look upusing the IP address associated with the HA function. That is, forexample, MS 102 may transmit to DNS 118 a reverse look-up requestmessage that includes the IP address associated with the HA function andcauses DNS 118 to use the IP address to look-up in its database a nameassociated with the IP address. In step 206, DNS 118 returns a nameassociated with the IP address. The name may be an Access Point Name(APN).

In step 208, MS 102 initiates a GPRS attach procedure to connect tonetwork 114. For example, while the IP session with server 120 is stillactive, MS 102 may have moved out of the coverage area of network 106and into the coverage area of network 108, thereby causing MS 102 toinitiate the GPRS attach procedure.

In step 210, MS 102 initiates PDF context activation (e.g., MS 102transmits to SGSN 112 an “Activate PDP context” request) and provides toSGSN 112 the name received in step 118 as part of the PDP contextactivation.

In step 212, SGSN 112 resolves the name (e.g., performs a DNS lookupusing the name) and receives one or more IP addresses, each of whichcorresponds to the GGSN function of the combined GGSN/HA 114. Forexample, in step 212, SGNS 112 may transmit, a network address lookuprequest to DNS 116, which request includes the name received from MS 102as part of the PDP context activation.

In step 214, the PDF context activation is completed, and the mobilestation receives the same IP address for the PDP context, as was used asthe Home Address in the WLAN access.

In this manner, the SGSN 112 will select the same GGSN/HA entity thatwas used by MS 102 when MS 102 had Internet access through network 106.

Referring now to FIG. 3, FIG. 3 further illustrates MS 102 according tosome embodiments of the invention.

As illustrated in FIG. 3, MS 102 includes: (1) a transceiver 302 fortransmitting and receiving data; (2) a storage device 304 (e.g.,non-volatile memory) for storing, among other things, an name 306received from the name server 118 in response to a reverse look-uprequest and software 308 for causing the device 102 to perform thefunctions described herein and illustrated in the flow chart of FIG. 2.

While various embodiments/variations of the present invention have beendescribed above, it should be understood that they have bean presentedby way of example only, and not limitation. Thus, the breadth and scopeof the present invention should not be limited by any of theabove-described exemplary embodiments. Further, unless stated, none ofthe above embodiments are mutually exclusive. Thus, the presentinvention may include any combinations and/or integrations of thefeatures of the various embodiments.

Additionally, while the processes described above and illustrated in thedrawings are shown as a sequence of steps, this was done solely for thesake of illustration. Accordingly, it is contemplated that some stepsmay be added, some steps may be omitted, and the order of the steps maybe re-arranged.

What is claimed is:
 1. A method in a mobile station for selecting acombined Gateway General packet radio service Support Node/Home Agent,GGSN/HA, node when accessing the internet using a Wireless Local AreaNetwork, WLAN, access network and when using a General Packet RadioService, GPRS, network, the method comprising: obtaining, at the mobilestation accessing internet using the WLAN access network, a networkaddress for a HA function of the combined GGSN/HA node; transmitting,from the mobile station, a request to a name server for a nameassociated with the network address for the HA function of the combinedGGSN/HA node; receiving, at the mobile station, from the name server inresponse to the request, the name associated with the network addressfor the HA function; initiating, at the mobile station, a GPRS networkattachment; and after initiating the GPRS network attachment,initiating, at the mobile station, a context activation, wherein thestep of initiating the context activation comprises transmitting, fromthe mobile station, the name associated with the network address for theHA function to a Serving GPRS Support Node, SGSN, wherein the SGSN isconfigured to select the same combined GGSN/HA node based on thereceived name when the mobile station accesses the internet using theGPRS network.
 2. The method of claim 1, wherein the step of selectingthe combined GGSN/HA node based on the received name comprisestransmitting a request to a second name server for a network addressassociated with the name.
 3. The method of claim 2, wherein the secondname server is different than the first recited name server.
 4. Themethod of claim 1, wherein the step of transmitting the request to thename server is performed prior to the step of initiating the GPRSattachment.
 5. The method of claim 1, wherein the step of initiating anetwork attachment comprises initiating a GPRS attachment, and the stepof initiating a context activation comprises initiating a Packet DataProtocol, PDP, context activation.
 6. A mobile station for selecting acombined Gateway General packet radio service Support Node/Home Agent,GGSN/HA, node when accessing the internet using a Wireless Local AreaNetwork, WLAN, access network and when using a General Packet RadioService, GPRS, network, wherein the mobile station is operable to:obtain a network address for a HA function of the combined GGSN/HA node,the HA function being used by the mobile station to access internetusing the WLAN access network; access the internet using the HA functionof the combined GGSN/HA node; transmit a request to a name server for aname associated with the network address for the HA function of thecombined GGSN/HA node; receive from the name server, in response to therequest, a name associated with the network address for the HA function;initiate a GPRS network attachment; and after initiating the GPRSnetwork attachment, transmit to a Serving GPRS Support Node, SGSN thename associated with the network address for the HA function andreceived from the name server; and wherein the SGSN is configured toselect the same combined GGSN/HA node based on the received name whenthe mobile station accesses the internet using the GPRS network.
 7. Themobile station of claim 6, wherein the mobile station is configured totransmit the request to the name server prior to initiating the networkattachment.
 8. The mobile station of claim 6, wherein the name server isconfigured to map the network address to a name.
 9. The mobile stationof claim 8, wherein the network address is an Internet Protocol, IP,address.
 10. A communication system, comprising: a mobile station, and aGeneral Packet Radio Service, GPRS, network comprising an Serving GPRSSupport Node, SGSN, a combined Gateway GPRS Support Node/Home Agent,GGSN/HA, node, a first name server, and a second name server, whereinthe mobile station is operable to: obtain a network address for a HAfunction of the combined GSN/HA node, the HA function being used by themobile station to access internet using a Wireless Local Area Network,WLAN, access network; access the internet using the HA function of thecombined GGSN/HA node; transmit a request to the first name server for aname associated with the network address for the HA function of thecombined GGSN/HA node; receive from the first name server, in responseto the request, the name associated with the network address for the HAfunction; initiate a GPRS network attachment; and after initiating theGPRS network attachment, transmit to the SGSN the name associated withthe network address for the HA function and received from the first nameserver; wherein the SGSN is configured to select the same combinedGGSN/HA node based on the received name when the mobile station accessesthe internet using the GPRS network, wherein the second name server isconfigured to map a network address associated with the HA function ofthe combined GGSN/HA node to the name, and wherein the first name serveris configured to map the name to a network address associated with theGGSN function of combined GGSN/HA node.
 11. The communication system ofclaim 10, wherein the name servers are Domain Name Servers, DNSs.